Enable the ability to disable the chat history UI (#2501)

docker/.env.example

frontend/src/components/CanViewChatHistory/index.jsx

frontend/src/components/SettingsSidebar/MenuOption/index.jsx

frontend/src/components/SettingsSidebar/index.jsx

frontend/src/models/system.js

frontend/src/pages/GeneralSettings/Chats/index.jsx

frontend/src/pages/GeneralSettings/EmbedChats/index.jsx

server/.env.example

server/endpoints/embedManagement.js

server/endpoints/system.js

server/models/systemSettings.js

server/utils/helpers/updateENV.js

server/utils/middleware/chatHistoryViewable.js